Gain in strength and muscular balance after balance training.

The isolated effect of balance training on muscle strength of the flexors and extensors of the knee, without accompanying strength training, has not been addressed in the past. Effects of a balance training program alone were compared to a strength training program. Balance and strength training were performed by 15 persons each for 6 weeks including 12 training units of 25 min. Balance training was performed on instability training devices such as rolling board, mini trampoline and large rubber ball. The 15 persons of the strength training group trained on machines for leg curls and on leg presses for 25 min per unit. Measurements for balance were performed with one-leg balance on a narrow edge and a tilting stabilometer for 30 s; maximum isometric strength was measured using an isokinetic device for each leg separately. The muscular balance between dominant and non-dominant leg was calculated. Strength gain was similar for the flexors and extensors in both groups. One-leg balance improved after balance training (P< 0.01) with a 100% increase over the strength training group (P < 0.05) and the stabilometer test for each person in the balance (P < 0.01), but not in the strength training group. In the balance group the initial difference between right and left diminished. The results indicate balance training to be effective for gain in muscular strength, and secondly, in contrast to strength training, equalisation of muscular imbalances may be achieved after balance training.     

Muscular strength and bone density with weight training in middle-aged women

Previous research has demonstrated positive correlations between bone mass and both physical activity and muscular strength. There is a paucity of information describing the specific type of exercise which most benefits the human skeleton. The effects of a 1 yr weight training program on 18 middle-aged women participating in an endurance dance program (E + W) compared with 17 other women in the endurance dance program only (E) and with 19 sedentary controls (C) were studied by measuring muscular strength and bone mineral density (BMD). Eighteen women in the E + W group demonstrated increases in all strength measurements, whereas the E and C groups either had smaller increases or had declined. A significant group x test interaction term, indicating that groups responded differently over time, was observed for nondominant isokinetic elbow flexion measured through the range of motion at a constant velocity of 60 degrees.s-1 (P less than 0.05), nondominant isokinetic elbow extension at 180 degrees.s-1 (P less than 0.01), and nondominant isokinetic elbow flexion at 180 degrees.s-1 (P less than 0.05). BMD did not change significantly except that a significant group x test interaction term appeared for the radius ultradistal site (P less than 0.01). BMD of the humerus and femoral Ward's triangle increased nonsignificantly in both E and E + W over the year. This weight training program increased muscular strength but did not increase measured bone mass.     

Striatal dopamine denervation and sensory integration for balance in middle-aged and older adults

The dopaminergic system of the basal ganglia has been implicated in the integration of sensory information important for balance based on studies in patients with Parkinson's disease. Striatal dopaminergic activity decreases with normal aging.

Objective

To investigate the relationship between regional striatal dopaminergic denervation and sensory information integration important for balance in middle-aged and older adults.

Methods

Community-dwelling subjects (N = 35; age 41–83) with no clinical diagnoses of conditions affecting balance underwent dynamic posturography testing (Sensory Organization Test/SOT) and C-11-beta-CFT dopamine transporter positron emission tomography.

Results

Reduced ventral striatal dopamine was significantly correlated with increased anterior–posterior sway in three SOT conditions. Specifically, during quiet standing (SOT Conditions #1, 2) and when repeatedly to sway-referenced visual environments (SOT Condition #3, Trial #3), pre-synaptic dopaminergic denervation in the anteroventral striatum explained over 20–25% of the variability in sway magnitude above and beyond that explained by age (p ≤ 0.01). Striatal dopaminergic denervation did not impact balance in sway-referenced floor conditions.

Conclusions

The SOT Condition #3 findings suggest that, in normal aging, the central ability to inhibit balance destabilizing vision-related postural control processes depends at least partially on striatal dopaminergic pathways. In contrast, striatal dopaminergic denervation does not appear to impair the ability to disengage destabilizing proprioceptive inputs and to trigger the vestibular control system during challenging sensory perturbations (SOT Conditions #4–6). Finally, quiet standing results (SOT Conditions #1, 2) justify the need to further investigate the impact of striatal dopaminergic denervation on the ability to tune muscle tone in healthy adults.     

Comparison of traditional and recent approaches in the promotion of balance and strength in older adults

Demographic change in industrialized countries produced an increase in the proportion of elderly people in our society, resulting in specific healthcare challenges. One such challenge is how to effectively deal with the increased risk of sustaining a fall and fall-related injuries in old age. Deficits in postural control and muscle strength represent important intrinsic fall risk factors. Thus, adequate training regimens need to be designed and applied that have the potential to reduce the rate of falling in older adults by countering these factors. Therefore, the purpose of this review is to compare traditional and recent approaches in the promotion of balance and strength in older adults. Traditionally, balance and resistance training programmes proved to be effective in improving balance and strength, and in reducing the number of falls. Yet, it was argued that these training protocols are not specific enough to induce adaptations in neuromuscular capacities that are specifically needed in actual balance-threatening situations (e.g. abilities to recover balance and to produce force explosively). Recent studies indicated that perturbation-based or multitask balance training and power/high-velocity resistance training have the potential to improve these specific capacities because they comply with the principle of training specificity. In fact, there is evidence that these specifically tailored training programmes are more effective in improving balance recovery mechanisms and muscle power than traditional training protocols. A few pilot studies have even shown that these recently designed training protocols have an impact on the reduction of fall incidence rate in older adults. Further research is needed to confirm these results and to elucidate the underlying mechanisms responsible for the adaptive processes.     

Maximal strength and power, endurance performance, and serum hormones in middle-aged and elderly men

PURPOSE: To examine maximal strength, power and muscle cross-sectional area, maximal and submaximal cycling endurance characteristics, and serum hormone concentrations of testosterone (T), free testosterone (FT), and cortisol (C) in middle-aged and elderly men. METHODS: Maximal knee extension force (isometric; MIF(KE)), power-load curves during concentric actions with loads ranging from 15% to 70% of 1 RM half-squat (1RM(HS)), muscle cross-sectional area of quadriceps femoris (CSA(QF)), workload, heart rate and lactate accumulation during incremental cycling, and serum hormone concentrations were measured in 26 middle-aged (M42 yr) and 21 elderly men (M65 yr). RESULTS: The 1RM(HS) (14%), MIF(KE) (24%) and CSA(QF) (13%) were lower in M65 than in M42 (P < 0.05-0.01). Power during submaximal actions was lower (P < 0.05-0.001) in M65 than in M42, but the differences disappeared when expressed relative to CSA(QF). Serum FT was in M42 higher (P < 0.05) than in M65. Maximal workload, maximal heart rate and peak blood lactate during cycling in M65 were 31%, 11%, and 20% lower than in M42 (P < 0.01). During submaximal cycling blood lactate rose more rapidly with increasing workload in M65 than in M42 (P < 0.05-0.01), but the differences disappeared when expressed relative to CSA(QF). Significant correlations existed between individual values of serum FT:C ratio, C and T, and those of muscle strength and maximal workload. CONCLUSION: Declines in maximal strength, muscle mass, and endurance performance seem to take place with increasing age, although muscle power and demand for aerobic energy per unit of muscle tissue during submaximal loads remain similar. The balance between anabolic and catabolic hormones in aging people over the years may be associated with age-related decreased strength and declines in maximal cycling workload.     

Decreased dynamic balance and dorsiflexion range of motion in young and middle-aged adults with chronic ankle instability

ObjectivesThe purpose of this study was to compare dynamic balance and weight-bearing dorsiflexion range of motion between young and middle-aged adults with and without chronic ankle instability.DesignCross-sectional.MethodsOne hundred and two young adults were classified as either having chronic ankle instability (n = 38), coper (n = 27) or a healthy-control (n = 37). A total of 55 middle-aged adults were identified as having chronic ankle instability (n = 16), coper (n = 15) or a healthy-control (n = 24). Participants completed the weight-bearing lunge test and the anterior, posteromedial and posterolateral reach directions of the star excursion balance test.ResultsMiddle-aged adults had shorter reach distances for each direction of the star excursion balance test compared to the young adults (p < 0.001). Regardless of age, participants with chronic ankle instability performed worse on the star excursion balance test compared to the coper (p < 0.05) and healthy-control group (p < 0.05). Similarly, participants with chronic ankle instability had less dorsiflexion compared to healthy-controls (p < 0.05), but not the coper group (p > 0.05).ConclusionsDeficits in dynamic postural control do not continue to decline with advancing age in individuals with chronic ankle instability, however, these impairments appear to continue to persist compared to uninjured controls.     

Effects of strength and endurance training on antioxidant enzyme gene expression and activity in middle-aged men

This study was aimed at investigating the effects of a 21-week period of progressive strength or endurance training on peripheral blood mononuclear cells (PBMC) antioxidant enzyme gene expression and activity in healthy middle-aged untrained men. Strength ( n =11) and endurance ( n =12) training were performed twice a week, including resistance exercises to activate all the main muscle groups or cycle-ergometer pedaling, respectively. mRNA levels of catalase, glutathione peroxidase (GPx), mitochondrial superoxide dismutase (MnSOD) and cytosolic superoxide dismutase (CuZnSOD) were increased after 21 weeks of strength training, while endurance training induced significant changes only in MnSOD and GPx mRNA levels. CuZnSOD protein content was significantly increased only in strength-trained subjects. The program of strength or endurance exercise training had no significant effects on the activity of any of the antioxidant enzymes. In conclusion, in a middle-aged population, 21 weeks of strength or endurance training was a sufficient stimulus to up-regulate mRNA levels of PBMC antioxidant enzymes, the strength training being a more optimal stimulus. However, the discrepancies between enzyme protein and mRNA levels suggest that the present systematic strength or endurance training period had no beneficial effects on enzymatic antioxidant defense mechanisms in previously untrained middle-aged men.     

Diversity in the imaging workforce

Culture is the coherent, learned, shared view a group of people has about life's concerns that ranks what is important, and instills attitudes about those things which are considered appropriate as well as prescribed behavior. It notes that some things have more significance than others. "Culture shock" is what happens when a person suddenly finds himself or herself in a place where "yes may mean "no," where a fixed price is negotiable, where to be kept in an outer office is not a cause for insult, and where laughter may signify anger Effective leaders should be able to vary their styles of management, such as leading, planning, organizing, motivating, decision making, staffing, and more importantly, communicating with groups of workers from different cultural backgrounds. Leaders need to perceive conflict as both a challenge and an opportunity. Awareness about team members' cultural similarities and differences is key to foster effective conflict resolution. Synergistic organizations transcend the distinct cultures of the team members. They use these differences as a resource in designing and developing organizational systems. Effective leaders must become a champion and capable of acting in many ways, not experts rigidly adhering to a single approach.     

Five times sit-to-stand following stroke: Relationship with strength and balance

BackgroundRising from a chair is an important functional measure after stroke. Originally developed as a measure of lower-limb strength, the five times sit-to-stand test has shown associations with other measures of impairment, such as balance ability. We aimed to compare strength and balance in their relationship with the five times sit-to-stand test following stroke.MethodsSixty-one participants following stroke were recruited from two hospitals in this cross-sectional observational study. Participants underwent assessment of the five times sit-to-stand (measured with a stopwatch), bilateral lower-limb muscle strength of seven individual muscle groups (hand-held dynamometry), and standing balance (computerised posturography). Partial correlations (controlling for body mass and height) were used to examine bivariate associations. Regression models with partial F-tests (including pertinent covariates) compared the contribution of strength (both limbs) and balance to five times sit-to-stand time.ResultsThe strength of the majority of lower-limb muscle groups (6/7) on the paretic side had a significant (P < 0.05) partial correlation with five times sit-to-stand time (r = -0.34 to -0.47) as did all balance measures (r = -0.27 to -0.56). In our regression models, knee extensor strength, total path length, and anteroposterior path velocity provided the largest contribution to five times sit-to-stand over covariates amongst strength and balance measures (R² = 16.6 to 17.9 %). Partial F-tests revealed that both lower-limb strength and balance contribute to five times sit-to-stand time independent of each other. A regression model containing knee extensor strength and anteroposterior path velocity accounted for 25.5 % of the variance in five times sit-to-stand time over covariates.ConclusionsThe strength of the knee extensor muscle group along with measures of standing balance ability (total path length and anteroposterior path velocity) both independently contribute to five times sit-to-stand time. Further research is required to examine how other important impairments post stroke impact five times sit-to-stand performance.     

Impact of strength and balance on Functional Gait Assessment performance in older adults

BackgroundThe Functional Gait Assessment (FGA) evaluates postural stability in gait and predicts fall risk in older adults. Individual tasks within the FGA consider aspects of mobility assumed to require strength and/or balance to complete. Identifying how quantitative measures of strength and balance relate to FGA performance would allow for more targeted interventions based on one’s pattern of performance on different tasks.Research QuestionIs performance on the FGA (total score and individual task scores) related to measures of strength and balance in healthy older adults?MethodsIn a cross-sectional study, healthy older adults (N = 46) were evaluated with the FGA, measures of knee extensor strength, and balance (static stance and weight shifting) (N = 46). Correlational analyses were performed between FGA scores (total and individual) and measures of strength and balance.ResultsTotal FGA performance was positively correlated with knee extensor strength (maximum torque and rate of torque development). Individual FGA tasks of walking backwards (task 9) and stair climbing (task 10) had the highest correlations with strength measures. Total FGA performance was correlated with reduced postural sway in static balance tasks, but not with balance performance on the weight shifting tasks. The individual FGA task that challenged proprioceptive (task 7) inputs for balance was associated with static balance.SignificanceThe total FGA score is related to domains of strength and static balance. The results indicate that the FGA can be influenced by reduced strength and balance. The pattern of performance on individual FGA tasks may indicate whether reduced postural stability in gait is related to deficits in strength or balance domains in this older population.     

Hamstring and quadriceps strength balance in normal and hamstring anterior cruciate ligament-reconstructed subjects.

OBJECTIVE: The purpose of this study was to evaluate and characterize the agonist-antagonist strength balance (hamstring/quadriceps [H/Q] ratio and dynamic control ratio [DCR]) about the knee specific to velocity, range of motion, and contraction type. We hypothesized that there would be systematic variation in the H/Q ratio and DCR based on knee joint angle, angular velocity, and contraction type. We also hypothesized that these ratios would be altered in the anterior cruciate ligament (ACL)-reconstructed group in favor of protecting the ACL graft (relative knee flexor strength when strain on the ACL is the greatest). DESIGN: Cross-sectional design. SETTING: A tertiary care sport medicine clinic. PATIENTS OR PARTICIPANTS: Sixteen subjects more than 1 year after hamstring tendon ACL reconstruction were compared with 30 active uninjured control subjects. INTERVENTIONS: Isokinetic strength testing was performed over 5 degrees to 95 degrees knee joint range of motion, 5 angular velocities (50, 100, 150, 200, 250 degrees/s), for concentric and eccentric contractions. MAIN OUTCOME MEASUREMENTS: Angle and velocity-matched H/Q ratio maps and DCR maps were produced for each group. Difference maps allowed quantification of the differences between the groups. RESULTS: Angle and velocity-matched H/Q ratio maps demonstrated systematic variation based on joint angle, velocity, and contraction type for both the control (H/Q, approximately 0-1.42; DCR, approximately 0-1.57) and the ACL-reconstructed group (H/Q, approximately 0-1.33; DCR, approximately 0-1.35). Difference maps demonstrate regional (angle and velocity-specific) alteration in the ratio between the ACL-reconstructed and control groups. CONCLUSIONS: Specific imbalances were demonstrated in the ACL-reconstructed group compared with control. In high knee flexion angles, the low H/Q ratio may represent a compromised ability of the hamstrings to stabilize the knee joint throughout the full range of motion. Near full knee extension shifts in favor of the knee flexors may represent an attempt to stabilize the knee at the angle of greatest ACL strain. These finding have implications for graft donor site selection and postoperative rehabilitation as well as provide insight into the neuromuscular control of the knee.     

Exercises of dynamic stability under unstable conditions increase muscle strength and balance ability in the elderly

The purpose of this study was to assess the effectiveness of a specific exercise intervention of mechanisms to control dynamic postural stability under unstable conditions in old adults. Forty‐seven old adults (65‐80 years) were assigned to 2 experimental groups (muscle strength group, n = 15; perturbation‐based group, n = 16) and a control group (n = 16). The strength group performed resistance exercises for leg and trunk muscles, while the perturbation‐based group exercised mechanisms of dynamic stability under unstable conditions. The training duration was 14 weeks, with training sessions twice a week for 1.5 hours. Muscle strength, balance ability, and balance recovery performance were investigated before and after the interventions using maximal isometric plantar flexion and knee extension contractions, the approach of the center of pressure to the anterior limits of stability and simulated forward falls. Both interventions increased balance recovery performance in simulated forward falls (81%, d  = 1.50 and 80%, d  = 1.08 in the muscle strength and perturbation‐based group, respectively), while the control group did not show any changes. Plantar flexor strength increased 20% (d  = 0.72) in the muscle strength and 23% (d  = 1.03) in the perturbation‐based group, while muscle strength of the knee extensors increased only in the muscle strength group (8%, d  = 0.76). On the other hand, only the perturbation‐based group showed a significant improvement of standing balance ability (38%, d = 1.61). We conclude that a perturbation‐based training program focusing on exercising mechanisms of dynamic stability in unstable conditions has the potential to enhance muscle strength as well as sensory information processing within the motor system during sudden and static balance tasks and, as a consequence, reduce the risk of falls in old adults.     

Recovery of lower extremity muscle strength and functional performance in middle-aged patients undergoing arthroscopic partial meniscectomy

Purpose

To investigate lower extremity muscle strength and functional performance before and after arthroscopic partial meniscectomy in middle-aged patients with degenerative meniscal tears. We hypothesized that patients would experience deficiencies in the affected leg at 3 months post-surgery, and that this deficiency would be normalized at 12 months following surgery.

Methods

Twenty-three patients (46 ± 6.5 years) meniscectomized in 2012 and 2013 were examined for knee extension, knee flexion, and hip abduction maximal isometric muscle strength (iMVC), rate of force development (RFD₂₀₀), and knee function (single-leg hop for distance and single-leg knee bends in 30 s.) before surgery, 3 and 12 months after surgery.

Results

Functional performance, knee extension iMVC and RFD₂₀₀ were impaired in the affected leg compared to the contralateral leg (p < 0.05) prior to surgery. A significant (Knee extension RFD₂₀₀, p = 0.033) or borderline significant improvement was observed in the affected leg compared to the contralateral leg from before to 12 months after surgery in most variables (leg × time interaction, n.s.).

Conclusion

Middle-aged patients undergoing surgery for degenerative medial meniscal tears show significant reductions in muscle strength, rapid force production, and functional performance in the leg undergoing surgery compared to the contralateral leg prior to surgery. These deficits in muscle strength and knee function were still present at 3 months post-surgery but were no longer observed at 12 months following surgery.

Level of evidence

III.

     

Effects of strength training and reduced training on functional performance and metabolic health indicators in middle-aged men

Changes in muscular fitness and metabolic health indicators were examined in 22 men (57.9 +/- 6.6 years, BMI 24.5 +/- 2.6 kg/m (2)) and 21 control men (58.2 +/- 6.1 years, BMI 25.4 +/- 2.8 kg/m (2)) during two consecutive 21-week periods: 1) whole body progressive strength training (ST: twice a week), and 2) continued reduced training (CRT: 3 ST sessions/2 weeks, n = 17 + 17). After the 21-week ST period, maximal strength of leg extensors increased in the ST group by 19.6 +/- 7.6 % vs. 2.8 +/- 4.4 % (p < 0.001) and also 10-m walking time and 10-step stair-climbing time shortened by - 17.2 +/- 7.6 % vs. 4.1 +/- 3.9 % (p < 0.01) and by - 8.2 +/- 6.8 % vs. - 3.0 +/- 6.8 % (p < 0.05) compared to the controls. Systolic blood pressure (BP) decreased in the ST group by - 4.4 +/- 6.7 % vs. 1.3 +/- 9.5 % (p < 0.05) compared to the controls after the ST period. Muscle strength as well as walking and stair-climbing times remained the same during the CRT. However, the changes in diastolic BP (- 8.9 +/- 8.7 % vs. - 1.0 +/- 6.6 %, p < 0.05) and fasting blood glucose concentrations (0.1 +/- 0.4 mmol/L vs. 0.3 +/- 0.4 mmol/L, p < 0.05) differed between the ST and control groups after the whole 42-week study period. Strength training has positive health effects in aging men by increasing maximal strength and functional performance and by decreasing resting blood pressure and high-intensity reduced strength training can maintain these health benefits.     

Effects of external light loading in power-type strength training on muscle power of the lower extremities in middle-aged subjects

The purpose of this study was to evaluate and compare the effects of training either with a light load or without any load in a 16-week power-type strength training intervention in sedentary middle-aged subjects. A total of 85 subjects participated in the study. In a supervised 22-week training intervention, including 16 weeks of power-type strength training, 42 subjects (Light Load group=LL group) trained with a 1.1 kg weight on each ankle and 43 subjects (No Load group=NOL group) trained without any external load. Subjects were comparable concerning their training attendance, and anthropometric and physiological characteristics. Training effects were evaluated by measuring Vertical Squat Jump (VSJ), 20-metre Running Time (20 mRT), Maximal Anaerobic Cycling Power of leg muscles (MACP), and Maximal Oxygen Uptake (V.O (2 max)) before and after the intervention. The LL group improved VSJ and MACP significantly (p<0.05), compared with the NOL group. No difference between the groups was observed in 20 mRT or in V.O (2 max). To conclude, the external loads of 2.2 kg, in total, increased the efficiency of power-type strength training in vertical jumps and in anaerobic power in leg muscles, but not in sprint running.     

The effects of acute experimental hip muscle pain on dynamic single-limb balance performance in healthy middle-aged adults

Middle-aged adults with painful hip conditions show balance impairments that are consistent with an increased risk of falls. Pathological changes at the hip, accompanied by pain, may accelerate pre-existing age-related balance deficits present in midlife. To consider the influence of pain alone, we investigated the effects of acute experimental hip muscle pain on dynamic single-limb balance in middle-aged adults. Thirty-four healthy adults aged 40–60 years formed two groups (Group-1: n = 16; Group-2: n = 18). Participants performed four tasks: Reactive Sideways Stepping (ReactSide); Star Excursion Balance Test (SEBT); Step Test; Single-Limb Squat; before and after an injection of hypertonic saline into the right gluteus medius muscle (Group-1) or ∼5 min rest (Group-2). Balance measures included the range and standard deviation of centre of pressure (CoP) movement in mediolateral and anterior-posterior directions, and CoP total path velocity (ReactSide, Squat); reach distance (SEBT); and number of completed steps (Step Test). Data were assessed using three-way analysis of variance. Motor outcomes were altered during the second repetition of tasks irrespective of exposure to experimental hip muscle pain or rest, with reduced SEBT anterior reach (−1.2 ± 4.1 cm, P = 0.027); greater step number during Step Test (1.5 ± 1.7 steps, P < 0.001); and slower CoP velocity during Single-Limb Squat (−4.9 ± 9.4 mms⁻¹, P = 0.024). Factors other than the presence of pain may play a greater role in balance impairments in middle-aged adults with hip pathologies.     

武警部队战士体能训练健康促进的思考

中国人民解放军军事训练条例总则第三条指出：“军事训练是提高部队战斗力的根本途径,是军队履行职能的主要保证,全军必须把军事训练作为和平时期部队工作的中心.”在武警部队,随着《军事训练和考核大纲》的不断完善,对军事训练给予了更多的关注,尤其是对体能训练的关注.在科技练兵的新时期,如何在保障战士身体健康的基础上,提高其体能水平,是部队卫生工作者必须要解决的问题.